Building units of the above type are known having supporting walls and of which the ceiling and floor are constructed as a wooden structure supported by the walls. The known building units are constructed in accordance with traditional construction methods.
Furthermore, GB-A-2 040 334 discloses a box-shaped, self-supporting building unit comprising a bottom element consisting of a frame and a plate and an upper element consisting of a frame and a plate, and four corner columns mutually joining together the bottom element and the upper element. When the building unit is to be assembled, said elements are initially assembled to a rigid supporting frame, which is subsequently transported to the building site, at which several such building units or frames are joined together, whereafter a number of operations are to be carried out, such as fitting of inner sheating, isolation and cladding.
Finally, U.S. Pat. No. 3,442,056 discloses a prefabricated building section comprising a floor element and a ceiling element comprising profiled metal beams forming a framework about the edge of the respective elements, and a wall element comprising profiled metal beams or columns along the lateral edges thereof.
When the building section is assembled, the wall elements arranged on the floor elements at the abutting beams thereof secured to each otheer, for instance by welding. Finally, the ceiling element is arranged on top of the wall elements and the abutting beams thereof secured to each other by welding.